Electrode-support for flaming-arc lamps.



R.SGOTT. ELECTRODE SUPPORT FOR. FLAMING ARG LAMPS. APPIQIOATION FILED JULY 27, 1907;

929,332. Patented July 27,1909.

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UNTTED STATES PATENT OFFTOE.

RALPH SCOTT, OF NEWARK, NEW JERSEY, ASSIGNOR TO SCOTT ELECTRICAL COMPANY, A

CORPORATION OF MAINE.

ELECTRODE-SUPPORT FOB FLAMING-ARC LAMPS.

Specification of Letters Patent.

Application filed July 2'7, 1907.

Patented July 2'7, 1909.

Serial No. 385,792.

To all whom it may concern:

lle it known that I, RALPH Scor'r, a citizen of the United States, residing at Newark, in the county of and tit-ate of New Jersey, have invented certain new and use ful Improvements in Electrode-Supports for Flaming-Arc Lamps, of which the following is a full, clear, and exact description.

My invention relates to are lamps of that 1 class or character having downwardly converging electrodes, the feed of which is regulated by a stop or steps against which one or both of the electrodes rest at their lower ends. Mechanism of this sort has been particularly used in flaming arc lamps, because this style of arc is lon and more adapted to downwardly converging electrodes than an are between plain carbons. ()n this account, the present invention has its main value and field of use in connection with flaming arcs, although, it is, of course, not limited thereto. Such a stop used with downwardly converging electrodes gives an ideal, simple manner of regulation, provided a practically operable material can be found for the stops. The material is exposed to intense heat and must not crack and disintegrate like porcelain, or melt. like the majority of metals, or form an are from its surface, or magnetically attract the arc and thereby destroy its symmetry. It is evident that a material like kaolin, or ordinary lire-proof clays will not answer, because these are insul'liciently heat conducting and become intensely heated to the point of disintegration where they contact with the arc. In some cases recourse has been had to specially constructed ribbed electrodes which permit the use of a stop remote from the zone of the arc and therefore not exposed to its intense heat.

I have experimented with various materials to attain a stop or ledge for the electrodes, but have been obliged to discard all the ordinary infusible earths, clays and vitre ous and refractory materials on account of their low conductivity of heat. This property causes them to become intensely heated where they contact with the are, so that they are weak and friable at the point where they are exposed to the weight and wear of the electrodes which they support. Under such circumstances, the material is rapidly disintegrated and rendered worthless. I then experimented with all of the ordinary available metals, which are the only materials having suflicient heat conducting properties. Metals being extremely good conductors of heat, keep at a substantially uniform temperature throughout their 'entire mass, so that the region in the zone of the arc remains relatively cool. Tn comparison to the heat of the arc, it is extremely cold, and this great difference in temperature is found to have a very favorable effect, because it seems to produce a repulsion of the are from the cold surface. It is probable that the volatile gases of the are are condensed in proximity to the chilled surface, so that there is no current carrying medium at this point. At any rate, the arc keeps about a sixteenth of an inch away from the cold metallic surface of the stop. But although experiments proved that a metallic stop was the ideal thing, I found no single metal would answer the requirements. Iron magnetically attracted the arc; brass, copper, and many other metals formed conducting oxids, so that they drew the arc to their own surfaces and served themselves as electrodes until they were fused or burned away. Zinc and aluminum both form oxids which are non-conducting, and in this respect these metals would serve as a stop since they eliminate these three difficulties above considered, that is1, they are non-magnetic and do not attract the arc; 2, they are heat conductive so as to remain comparatively cool even where exposed to the arc Zone, and 3, they form insulating oxids so that they will not allow an are on their own surfaces, and thereby serve as electrodes. These metals therefore answer to a certain extent, but they do not fulfil the fourth requirement mentioned in the preliminary part of the specification. These metals are relatively fusible, zinc melting at 412 (1., and aluminum at a red heat. This relatively low fusing point is a grave objection to these materials. By experiment, I have discovered, however, that an alloy including both of these metals, in certain proportions has all the properties abovementioned of zinc and aluminum individually, except that the fusing point is very much higher. To make it even higher, some such metal as copper may be added. The fusing point of this alloy is so high that it is out of the range of possible fusion by the are when used as a stop for electrodes in accordance with my invent-ion. A stop formed of an alloy of zinc and aluminum or having a considerable proportion thereof, therefore answers perfectly all the requirements for flaming and other are lamps when used as an electrode support.

In the drawings, I have illustrated an electrode support used with the downwardly converging electrodes of a flaming arc lamp.

Figure 1 shows a single stop for one electrode of a pair, and Fig. 2 shows both electrodes having stops.

A and B indicate the electrodes, and C the stop made of an alloy of equal parts zinc and aluminum, and preferably in the form of a circular button centrally pivoted at D and having a rounded edge where it contacts with the are. This structure permits the stop to be swiveled on its axis so as to present a new surface should any point become worn or unduly oxidized.

Vhile I have shown ordinary circular electrodes, 1 do not, of course, desire to be limited or restricted thereto, since specially made electrodes with a lateral rib or ribs to engage the stop may be used if desired.

lVhat I claim is A. stop for an electrode of an arc lamp, comprising a button of substantially equal parts zinc and aluminum.

In witness whereof I subscribe my signature in the presence of two witnesses.

RALPH SCOTT.

lVit-nesses VALDO M. CIIAPIN, JAMES DANTONIO. 

